pylint: upgrade to 1.3.1

third_party/pylint/checkers/typecheck.py

-# Copyright (c) 2006-2010 LOGILAB S.A. (Paris, FRANCE).
+# Copyright (c) 2006-2013 LOGILAB S.A. (Paris, FRANCE).
 # http://www.logilab.fr/ -- mailto:contact@logilab.fr
 #
 # This program is free software; you can redistribute it and/or modify it under
 # the terms of the GNU General Public License as published by the Free Software
 # Foundation; either version 2 of the License, or (at your option) any later
 # version.
 #
 # This program is distributed in the hope that it will be useful, but WITHOUT
 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 # FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License along with
 # this program; if not, write to the Free Software Foundation, Inc.,
-# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
-"""try to find more bugs in the code using astng inference capabilities
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+"""try to find more bugs in the code using astroid inference capabilities
 """
 
 import re
 import shlex
 
-from logilab import astng
-from logilab.astng import InferenceError, NotFoundError, YES, Instance
+import astroid
+from astroid import InferenceError, NotFoundError, YES, Instance
+from astroid.bases import BUILTINS
 
-from pylint.interfaces import IASTNGChecker
+from pylint.interfaces import IAstroidChecker
 from pylint.checkers import BaseChecker
 from pylint.checkers.utils import safe_infer, is_super, check_messages
 
 MSGS = {
     'E1101': ('%s %r has no %r member',
+              'no-member',
               'Used when a variable is accessed for an unexistent member.'),
     'E1102': ('%s is not callable',
+              'not-callable',
               'Used when an object being called has been inferred to a non \
               callable object'),
     'E1103': ('%s %r has no %r member (but some types could not be inferred)',
+              'maybe-no-member',
               'Used when a variable is accessed for an unexistent member, but \
-              astng was not able to interpret all possible types of this \
+              astroid was not able to interpret all possible types of this \
               variable.'),
     'E1111': ('Assigning to function call which doesn\'t return',
+              'assignment-from-no-return',
               'Used when an assignment is done on a function call but the \
               inferred function doesn\'t return anything.'),
     'W1111': ('Assigning to function call which only returns None',
+              'assignment-from-none',
               'Used when an assignment is done on a function call but the \
               inferred function returns nothing but None.'),
 
-    'E1120': ('No value passed for parameter %s in function call',
+    'E1120': ('No value for argument %s in %s call',
+              'no-value-for-parameter',
               'Used when a function call passes too few arguments.'),
-    'E1121': ('Too many positional arguments for function call',
+    'E1121': ('Too many positional arguments for %s call',
+              'too-many-function-args',
               'Used when a function call passes too many positional \
               arguments.'),
-    'E1122': ('Duplicate keyword argument %r in function call',
+    'E1122': ('Duplicate keyword argument %r in %s call',
+              'duplicate-keyword-arg',
               'Used when a function call passes the same keyword argument \
-              multiple times.'),
-    'E1123': ('Passing unexpected keyword argument %r in function call',
+              multiple times.',
+              {'maxversion': (2, 6)}),
+    'E1123': ('Unexpected keyword argument %r in %s call',
+              'unexpected-keyword-arg',
               'Used when a function call passes a keyword argument that \
               doesn\'t correspond to one of the function\'s parameter names.'),
-    'E1124': ('Multiple values passed for parameter %r in function call',
+    'E1124': ('Argument %r passed by position and keyword in %s call',
+              'redundant-keyword-arg',
               'Used when a function call would result in assigning multiple \
               values to a function parameter, one value from a positional \
               argument and one from a keyword argument.'),
+    'E1125': ('Missing mandatory keyword argument %r in %s call',
+              'missing-kwoa',
+              ('Used when a function call does not pass a mandatory'
+               ' keyword-only argument.'),
+              {'minversion': (3, 0)}),
+    'E1126': ('Sequence index is not an int, slice, or instance with __index__',
+              'invalid-sequence-index',
+              'Used when a sequence type is indexed with an invalid type. '
+              'Valid types are ints, slices, and objects with an __index__ '
+              'method.'),
+    'E1127': ('Slice index is not an int, None, or instance with __index__',
+              'invalid-slice-index',
+              'Used when a slice index is not an integer, None, or an object \
+               with an __index__ method.'),
     }
 
+# builtin sequence types in Python 2 and 3.
+SEQUENCE_TYPES = set(['str', 'unicode', 'list', 'tuple', 'bytearray',
+                      'xrange', 'range', 'bytes', 'memoryview'])
+
+def _determine_callable(callable_obj):
+    # Ordering is important, since BoundMethod is a subclass of UnboundMethod,
+    # and Function inherits Lambda.
+    if isinstance(callable_obj, astroid.BoundMethod):
+        # Bound methods have an extra implicit 'self' argument.
+        return callable_obj, 1, callable_obj.type
+    elif isinstance(callable_obj, astroid.UnboundMethod):
+        return callable_obj, 0, 'unbound method'
+    elif isinstance(callable_obj, astroid.Function):
+        return callable_obj, 0, callable_obj.type
+    elif isinstance(callable_obj, astroid.Lambda):
+        return callable_obj, 0, 'lambda'
+    elif isinstance(callable_obj, astroid.Class):
+        # Class instantiation, lookup __new__ instead.
+        # If we only find object.__new__, we can safely check __init__
+        # instead.
+        try:
+            # Use the last definition of __new__.
+            new = callable_obj.local_attr('__new__')[-1]
+        except astroid.NotFoundError:
+            new = None
+
+        if not new or new.parent.scope().name == 'object':
+            try:
+                # Use the last definition of __init__.
+                callable_obj = callable_obj.local_attr('__init__')[-1]
+            except astroid.NotFoundError:
+                # do nothing, covered by no-init.
+                raise ValueError
+        else:
+            callable_obj = new
+
+        if not isinstance(callable_obj, astroid.Function):
+            raise ValueError
+        # both have an extra implicit 'cls'/'self' argument.
+        return callable_obj, 1, 'constructor'
+    else:
+        raise ValueError
+
 class TypeChecker(BaseChecker):
     """try to find bugs in the code using type inference
     """
 
-    __implements__ = (IASTNGChecker,)
+    __implements__ = (IAstroidChecker,)
 
     # configuration section name
     name = 'typecheck'
     # messages
     msgs = MSGS
     priority = -1
     # configuration options
     options = (('ignore-mixin-members',
                 {'default' : True, 'type' : 'yn', 'metavar': '<y_or_n>',
                  'help' : 'Tells whether missing members accessed in mixin \
 class should be ignored. A mixin class is detected if its name ends with \
 "mixin" (case insensitive).'}
-                ),
-
+               ),
+               ('ignored-modules',
+                {'default': (),
+                 'type': 'csv',
+                 'metavar': '<module names>',
+                 'help': 'List of module names for which member attributes \
+should not be checked (useful for modules/projects where namespaces are \
+manipulated during runtime and thus existing member attributes cannot be \
+deduced by static analysis'},
+               ),
                ('ignored-classes',
                 {'default' : ('SQLObject',),
                  'type' : 'csv',
                  'metavar' : '<members names>',
                  'help' : 'List of classes names for which member attributes \
 should not be checked (useful for classes with attributes dynamically set).'}
-                 ),
+               ),
 
                ('zope',
                 {'default' : False, 'type' : 'yn', 'metavar': '<y_or_n>',
                  'help' : 'When zope mode is activated, add a predefined set \
 of Zope acquired attributes to generated-members.'}
-                ),
+               ),
                ('generated-members',
-                {'default' : (
-        'REQUEST', 'acl_users', 'aq_parent'),
+                {'default' : ('REQUEST', 'acl_users', 'aq_parent'),
                  'type' : 'string',
                  'metavar' : '<members names>',
                  'help' : 'List of members which are set dynamically and \
 missed by pylint inference system, and so shouldn\'t trigger E0201 when \
 accessed. Python regular expressions are accepted.'}
-                ),
-        )
+               ),
+              )
 
     def open(self):
         # do this in open since config not fully initialized in __init__
         self.generated_members = list(self.config.generated_members)
         if self.config.zope:
             self.generated_members.extend(('REQUEST', 'acl_users', 'aq_parent'))
 
     def visit_assattr(self, node):
-        if isinstance(node.ass_type(), astng.AugAssign):
+        if isinstance(node.ass_type(), astroid.AugAssign):
             self.visit_getattr(node)
 
     def visit_delattr(self, node):
         self.visit_getattr(node)
 
-    @check_messages('E1101', 'E1103')
+    @check_messages('no-member', 'maybe-no-member')
     def visit_getattr(self, node):
         """check that the accessed attribute exists
 
         to avoid to much false positives for now, we'll consider the code as
         correct if a single of the inferred nodes has the accessed attribute.
 
         function/method, super call and metaclasses are ignored
         """
         # generated_members may containt regular expressions
         # (surrounded by quote `"` and followed by a comma `,`)
         # REQUEST,aq_parent,"[a-zA-Z]+_set{1,2}"' =>
         # ('REQUEST', 'aq_parent', '[a-zA-Z]+_set{1,2}')
         if isinstance(self.config.generated_members, str):
             gen = shlex.shlex(self.config.generated_members)
             gen.whitespace += ','
+            gen.wordchars += '[]-+'
             self.config.generated_members = tuple(tok.strip('"') for tok in gen)
         for pattern in self.config.generated_members:
             # attribute is marked as generated, stop here
             if re.match(pattern, node.attrname):
                 return
         try:
             infered = list(node.expr.infer())
         except InferenceError:
             return
         # list of (node, nodename) which are missing the attribute
         missingattr = set()
         ignoremim = self.config.ignore_mixin_members
         inference_failure = False
         for owner in infered:
             # skip yes object
             if owner is YES:
                 inference_failure = True
                 continue
             # skip None anyway
-            if isinstance(owner, astng.Const) and owner.value is None:
+            if isinstance(owner, astroid.Const) and owner.value is None:
                 continue
             # XXX "super" / metaclass call
             if is_super(owner) or getattr(owner, 'type', None) == 'metaclass':
                 continue
             name = getattr(owner, 'name', 'None')
             if name in self.config.ignored_classes:
                 continue
             if ignoremim and name[-5:].lower() == 'mixin':
                 continue
             try:
                 if not [n for n in owner.getattr(node.attrname)
-                        if not isinstance(n.statement(), astng.AugAssign)]:
+                        if not isinstance(n.statement(), astroid.AugAssign)]:
                     missingattr.add((owner, name))
                     continue
             except AttributeError:
                 # XXX method / function
                 continue
             except NotFoundError:
-                if isinstance(owner, astng.Function) and owner.decorators:
-                   continue
+                if isinstance(owner, astroid.Function) and owner.decorators:
+                    continue
                 if isinstance(owner, Instance) and owner.has_dynamic_getattr():
                     continue
-                # explicit skipping of optparse'Values class
-                if owner.name == 'Values' and owner.root().name == 'optparse':
+                # explicit skipping of module member access
+                if owner.root().name in self.config.ignored_modules:
                     continue
                 missingattr.add((owner, name))
                 continue
             # stop on the first found
             break
         else:
             # we have not found any node with the attributes, display the
             # message for infered nodes
             done = set()
             for owner, name in missingattr:
                 if isinstance(owner, Instance):
                     actual = owner._proxied
                 else:
                     actual = owner
                 if actual in done:
                     continue
                 done.add(actual)
                 if inference_failure:
-                    msgid = 'E1103'
+                    msgid = 'maybe-no-member'
                 else:
-                    msgid = 'E1101'
+                    msgid = 'no-member'
                 self.add_message(msgid, node=node,
                                  args=(owner.display_type(), name,
                                        node.attrname))
 
-
+    @check_messages('assignment-from-no-return', 'assignment-from-none')
     def visit_assign(self, node):
         """check that if assigning to a function call, the function is
         possibly returning something valuable
         """
-        if not isinstance(node.value, astng.CallFunc):
+        if not isinstance(node.value, astroid.CallFunc):
             return
         function_node = safe_infer(node.value.func)
         # skip class, generator and incomplete function definition
-        if not (isinstance(function_node, astng.Function) and
+        if not (isinstance(function_node, astroid.Function) and
                 function_node.root().fully_defined()):
             return
         if function_node.is_generator() \
                or function_node.is_abstract(pass_is_abstract=False):
             return
-        returns = list(function_node.nodes_of_class(astng.Return,
-                                                    skip_klass=astng.Function))
+        returns = list(function_node.nodes_of_class(astroid.Return,
+                                                    skip_klass=astroid.Function))
         if len(returns) == 0:
-            self.add_message('E1111', node=node)
+            self.add_message('assignment-from-no-return', node=node)
         else:
             for rnode in returns:
-                if not (isinstance(rnode.value, astng.Const)
-                        and rnode.value.value is None):
+                if not (isinstance(rnode.value, astroid.Const)
+                        and rnode.value.value is None
+                        or rnode.value is None):
                     break
             else:
-                self.add_message('W1111', node=node)
+                self.add_message('assignment-from-none', node=node)
 
+    def _check_uninferable_callfunc(self, node):
+        """
+        Check that the given uninferable CallFunc node does not
+        call an actual function.
+        """
+        if not isinstance(node.func, astroid.Getattr):
+            return
+
+        # Look for properties. First, obtain
+        # the lhs of the Getattr node and search the attribute
+        # there. If that attribute is a property or a subclass of properties,
+        # then most likely it's not callable.
+
+        # TODO: since astroid doesn't understand descriptors very well
+        # we will not handle them here, right now.
+
+        expr = node.func.expr
+        klass = safe_infer(expr)
+        if (klass is None or klass is astroid.YES or
+                not isinstance(klass, astroid.Instance)):
+            return
+
+        try:
+            attrs = klass._proxied.getattr(node.func.attrname)
+        except astroid.NotFoundError:
+            return
+
+        stop_checking = False
+        for attr in attrs:
+            if attr is astroid.YES:
+                continue
+            if stop_checking:
+                break
+            if not isinstance(attr, astroid.Function):
+                continue
+
+            # Decorated, see if it is decorated with a property
+            if not attr.decorators:
+                continue
+            for decorator in attr.decorators.nodes:
+                if not isinstance(decorator, astroid.Name):
+                    continue
+                try:
+                    for infered in decorator.infer():
+                        property_like = False
+                        if isinstance(infered, astroid.Class):
+                            if (infered.root().name == BUILTINS and
+                                    infered.name == 'property'):
+                                property_like = True
+                            else:
+                                for ancestor in infered.ancestors():
+                                    if (ancestor.name == 'property' and
+                                            ancestor.root().name == BUILTINS):
+                                        property_like = True
+                                        break
+                            if property_like:
+                                self.add_message('not-callable', node=node,
+                                                 args=node.func.as_string())
+                                stop_checking = True
+                                break
+                except InferenceError:
+                    pass
+                if stop_checking:
+                    break
+
+    @check_messages(*(list(MSGS.keys())))
     def visit_callfunc(self, node):
         """check that called functions/methods are inferred to callable objects,
         and that the arguments passed to the function match the parameters in
         the inferred function's definition
         """
-
         # Build the set of keyword arguments, checking for duplicate keywords,
         # and count the positional arguments.
         keyword_args = set()
         num_positional_args = 0
         for arg in node.args:
-            if isinstance(arg, astng.Keyword):
+            if isinstance(arg, astroid.Keyword):
                 keyword = arg.arg
                 if keyword in keyword_args:
-                    self.add_message('E1122', node=node, args=keyword)
+                    self.add_message('duplicate-keyword-arg', node=node,
+                                     args=(keyword, 'function'))
                 keyword_args.add(keyword)
             else:
                 num_positional_args += 1
 
         called = safe_infer(node.func)
         # only function, generator and object defining __call__ are allowed
         if called is not None and not called.callable():
-            self.add_message('E1102', node=node, args=node.func.as_string())
+            self.add_message('not-callable', node=node,
+                             args=node.func.as_string())
 
-        # Note that BoundMethod is a subclass of UnboundMethod (huh?), so must
-        # come first in this 'if..else'.
-        if isinstance(called, astng.BoundMethod):
-            # Bound methods have an extra implicit 'self' argument.
-            num_positional_args += 1
-        elif isinstance(called, astng.UnboundMethod):
-            if called.decorators is not None:
-                for d in called.decorators.nodes:
-                    if isinstance(d, astng.Name) and (d.name == 'classmethod'):
-                        # Class methods have an extra implicit 'cls' argument.
-                        num_positional_args += 1
-                        break
-        elif (isinstance(called, astng.Function) or
-              isinstance(called, astng.Lambda)):
-            pass
-        else:
+        self._check_uninferable_callfunc(node)
+
+        try:
+            called, implicit_args, callable_name = _determine_callable(called)
+        except ValueError:
+            # Any error occurred during determining the function type, most of
+            # those errors are handled by different warnings.
             return
-
+        num_positional_args += implicit_args
         if called.args.args is None:
             # Built-in functions have no argument information.
             return
 
-        if len( called.argnames() ) != len( set( called.argnames() ) ):
+        if len(called.argnames()) != len(set(called.argnames())):
             # Duplicate parameter name (see E9801).  We can't really make sense
             # of the function call in this case, so just return.
             return
 
         # Analyze the list of formal parameters.
         num_mandatory_parameters = len(called.args.args) - len(called.args.defaults)
         parameters = []
         parameter_name_to_index = {}
         for i, arg in enumerate(called.args.args):
-            if isinstance(arg, astng.Tuple):
+            if isinstance(arg, astroid.Tuple):
                 name = None
                 # Don't store any parameter names within the tuple, since those
                 # are not assignable from keyword arguments.
             else:
-                if isinstance(arg, astng.Keyword):
+                if isinstance(arg, astroid.Keyword):
                     name = arg.arg
                 else:
-                    assert isinstance(arg, astng.AssName)
+                    assert isinstance(arg, astroid.AssName)
                     # This occurs with:
                     #    def f( (a), (b) ): pass
                     name = arg.name
                 parameter_name_to_index[name] = i
             if i >= num_mandatory_parameters:
                 defval = called.args.defaults[i - num_mandatory_parameters]
             else:
                 defval = None
             parameters.append([(name, defval), False])
 
+        kwparams = {}
+        for i, arg in enumerate(called.args.kwonlyargs):
+            if isinstance(arg, astroid.Keyword):
+                name = arg.arg
+            else:
+                assert isinstance(arg, astroid.AssName)
+                name = arg.name
+            kwparams[name] = [called.args.kw_defaults[i], False]
+
         # Match the supplied arguments against the function parameters.
 
         # 1. Match the positional arguments.
         for i in range(num_positional_args):
             if i < len(parameters):
                 parameters[i][1] = True
             elif called.args.vararg is not None:
                 # The remaining positional arguments get assigned to the *args
                 # parameter.
                 break
             else:
                 # Too many positional arguments.
-                self.add_message('E1121', node=node)
+                self.add_message('too-many-function-args',
+                                 node=node, args=(callable_name,))
                 break
 
         # 2. Match the keyword arguments.
         for keyword in keyword_args:
             if keyword in parameter_name_to_index:
                 i = parameter_name_to_index[keyword]
                 if parameters[i][1]:
                     # Duplicate definition of function parameter.
-                    self.add_message('E1124', node=node, args=keyword)
+                    self.add_message('redundant-keyword-arg',
+                                     node=node, args=(keyword, callable_name))
                 else:
                     parameters[i][1] = True
+            elif keyword in kwparams:
+                if kwparams[keyword][1]:  # XXX is that even possible?
+                    # Duplicate definition of function parameter.
+                    self.add_message('redundant-keyword-arg', node=node,
+                                     args=(keyword, callable_name))
+                else:
+                    kwparams[keyword][1] = True
             elif called.args.kwarg is not None:
                 # The keyword argument gets assigned to the **kwargs parameter.
                 pass
             else:
                 # Unexpected keyword argument.
-                self.add_message('E1123', node=node, args=keyword)
+                self.add_message('unexpected-keyword-arg', node=node,
+                                 args=(keyword, callable_name))
 
         # 3. Match the *args, if any.  Note that Python actually processes
         #    *args _before_ any keyword arguments, but we wait until after
         #    looking at the keyword arguments so as to make a more conservative
         #    guess at how many values are in the *args sequence.
         if node.starargs is not None:
             for i in range(num_positional_args, len(parameters)):
                 [(name, defval), assigned] = parameters[i]
                 # Assume that *args provides just enough values for all
                 # non-default parameters after the last parameter assigned by
@@ skipping 13 matching lines @@
                     parameters[i][1] = True
                 else:
                     # **kwargs can't assign to tuples.
                     pass
 
         # Check that any parameters without a default have been assigned
         # values.
         for [(name, defval), assigned] in parameters:
             if (defval is None) and not assigned:
                 if name is None:
-                    display = '<tuple>'
+                    display_name = '<tuple>'
                 else:
                     display_name = repr(name)
-                self.add_message('E1120', node=node, args=display_name)
+                self.add_message('no-value-for-parameter', node=node,
+                                 args=(display_name, callable_name))
+
+        for name in kwparams:
+            defval, assigned = kwparams[name]
+            if defval is None and not assigned:
+                self.add_message('missing-kwoa', node=node,
+                                 args=(name, callable_name))
+
+    @check_messages('invalid-sequence-index')
+    def visit_extslice(self, node):
+        # Check extended slice objects as if they were used as a sequence
+        # index to check if the object being sliced can support them
+        return self.visit_index(node)
+
+    @check_messages('invalid-sequence-index')
+    def visit_index(self, node):
+        if not node.parent or not hasattr(node.parent, "value"):
+            return
+
+        # Look for index operations where the parent is a sequence type.
+        # If the types can be determined, only allow indices to be int,
+        # slice or instances with __index__.
+
+        parent_type = safe_infer(node.parent.value)
+
+        if not isinstance(parent_type, (astroid.Class, astroid.Instance)):
+            return
+
+        # Determine what method on the parent this index will use
+        # The parent of this node will be a Subscript, and the parent of that
+        # node determines if the Subscript is a get, set, or delete operation.
+        operation = node.parent.parent
+        if isinstance(operation, astroid.Assign):
+            methodname = '__setitem__'
+        elif isinstance(operation, astroid.Delete):
+            methodname = '__delitem__'
+        else:
+            methodname = '__getitem__'
+
+        # Check if this instance's __getitem__, __setitem__, or __delitem__, as
+        # appropriate to the statement, is implemented in a builtin sequence
+        # type. This way we catch subclasses of sequence types but skip classes
+        # that override __getitem__ and which may allow non-integer indices.
+        try:
+            methods = parent_type.getattr(methodname)
+            if methods is astroid.YES:
+                return
+            itemmethod = methods[0]
+        except (astroid.NotFoundError, IndexError):
+            return
+
+        if not isinstance(itemmethod, astroid.Function):
+            return
+
+        if itemmethod.root().name != BUILTINS:
+            return
+
+        if not itemmethod.parent:
+            return
+
+        if itemmethod.parent.name not in SEQUENCE_TYPES:
+            return
+
+        # For ExtSlice objects coming from visit_extslice, no further
+        # inference is necessary, since if we got this far the ExtSlice
+        # is an error.
+        if isinstance(node, astroid.ExtSlice):
+            index_type = node
+        else:
+            index_type = safe_infer(node)
+
+        if index_type is None or index_type is astroid.YES:
+            return
+
+        # Constants must be of type int
+        if isinstance(index_type, astroid.Const):
+            if isinstance(index_type.value, int):
+                return
+        # Instance values must be int, slice, or have an __index__ method
+        elif isinstance(index_type, astroid.Instance):
+            if index_type.pytype() in (BUILTINS + '.int', BUILTINS + '.slice'):
+                return
+
+            try:
+                index_type.getattr('__index__')
+                return
+            except astroid.NotFoundError:
+                pass
+
+        # Anything else is an error
+        self.add_message('invalid-sequence-index', node=node)
+
+    @check_messages('invalid-slice-index')
+    def visit_slice(self, node):
+        # Check the type of each part of the slice
+        for index in (node.lower, node.upper, node.step):
+            if index is None:
+                continue
+
+            index_type = safe_infer(index)
+
+            if index_type is None or index_type is astroid.YES:
+                continue
+
+            # Constants must of type int or None
+            if isinstance(index_type, astroid.Const):
+                if isinstance(index_type.value, (int, type(None))):
+                    continue
+            # Instance values must be of type int, None or an object
+            # with __index__
+            elif isinstance(index_type, astroid.Instance):
+                if index_type.pytype() in (BUILTINS + '.int',
+                                           BUILTINS + '.NoneType'):
+                    continue
+
+                try:
+                    index_type.getattr('__index__')
+                    return
+                except astroid.NotFoundError:
+                    pass
+
+            # Anything else is an error
+            self.add_message('invalid-slice-index', node=node)
 
 def register(linter):
     """required method to auto register this checker """
     linter.register_checker(TypeChecker(linter))